Safety projectile percussion primer

ABSTRACT

A locking pin extends between the firing pin and primer element of a projectile to prevent their engagement during transport and while within the barrel of the firing device because of the radial abutment of a safety member that will move axially out of engagement only after the projectile has left the barrel of the firing device so that the locking member may move radially outward to arm the device. The safety member may be the radial abutment of the cartridge case tubular wall before firing and the interior surfaces of the firing device barrel during firing, with the locking member preferably being spring urged outwardly. Also, the safety member may be an axially extending pin prevented from rearward movement out of engagement with the locking member by a spacer disc separable upon exit from the barrel or the cartridge bottom piece.

I United States Patent [111 3,576,165

[72] In n rs Heinz Gall/lick; 2,108,818 2/1938 Huffet a1 102/76X RudolfStahlmann, Furth, Germany 2,371,151 3/1945 Church et a1. 102/76X 1 1 ppLNo. 719,542 2,513,536 7/1950 Wellington..... 102/76 1 Filed p 1968 2,630,066 3/1950 Ponder et al 102/76X 1 Patented Apr-27,1971 2,741,177 4/1956 Richards et a1. 102/76x [73] Assign Dyn mi N l Akti ngesell haf 2,960,037 11/1960 Raech et a1 102/76 Froisdorf, Germany 3,211,098 10/1965 Stadler et a1 102/49.1x Pnomy g t Primary ExaminerBenjamin A. Borchelt [311 B52736y Assistant Examiner-Thomas H. Webb Attorney-Craig, Antonelli, Stewart and Hill [54] SAFETY PROJECTILE PERCUSSION PRIMER 14 Claims, 8 Drawing Figs. Al iSTRACT: A lockmg p n extends between the firmg pm and r primer element ofa pro ecnle to prevent them engagement [52] U.S.Cl 102/73, during transport and while within the barrel f the fi i 102,49, 102,76 device because of the radial abutment of a safety member that [51] Int. Cl F42c 15/04, wlll move axlally out of engagement only after the projectile Y F426 15/ F42c 15/00 has left the barrel of the firing device so that the locking [50] Field of Search 102/49.1, member may move lradially outward to arm the device The 78 safety member may be the radial abutment of the cartridge case tubular wall before firing and the interior surfaces of the [56] References cued firing device barrel during firing, with the locking member UNITED STATES PATENTS preferably being spring urged outwardly. Also, the safety 1,375,466 4/1921 Ragsdale 102/78 member may be an axially extending pin prevented from rear- 2,692,557 10/ 1954 Wales, Jr. 102/78 ward movement out of engagement with the locking member 1,806,877 5/1931 Hale 102/80 by a spacer disc separable upon exit from the barrel or the 1,933,608 11/1933 Teitsheid l02/76(1) cartridge bottom piece.

II t 1 l l l 1 I I PATENTED APR27 IBYI SHEET 1 BF 2 FIG. 5b

INVENTORS HEINZ GAWLICK RUDOLF STAHLMANN ATTORNEYS TENTEU m2 1 I97] INVENTORS HEINZ GAWLICK RUDOLF STAHLMANN BY @I ATTORNEYS SAFETY PROJECTILE PERCUSSION PRIMER BACKGROUND OF THE INVENTION It is known to provide a primer for a subcaliber training trench mortar with relatively axially movable firing pin and primer elements in an axially extending central bore of the projectile, which primer element has a primer composition for the ignition of the projectile charge. To prevent relative movements of the elements, a compression spring has been provided therebetween. Upon impact of the projectile on the target, the primer element is forwardly displaced due to its inertia against the force of the compression spring for ignition upon engagement with the firing pin. With such a device, there is the essential disadvantage that it is not safe either in the barrel or after exiting from the barrel, because it is armed at all times. A strong compression spring is desired for safety reasons but yet is disadvantageous with respect to primer sensitivity upon striking the target; therefore, with low initial velocities, V,,, the primer may not be ignited upon striking the target and only limited safety is provided by the compression spring because of a compromise between the conflicting requirements of the spring.

It has been proposed to provide the percussion primer with a safety device that can be armed by the inertial effect of locking balls. Although safety is assured during transport, within the barrel and after leaving the barrel, there is the danger with such a safety device that, under unfavorable conditions, the locking balls disposed between the primer element and the firing pin element will not reach their arming position under the influence of inertia and thus continue to block the desired relative movement of the firing pin and primer element so that there is thus the unfavorable high probability of a projectile reaching the target without being armed.

SUMMARY OF THE INVENTION The present invention relates to a percussion primer for rounds of ammunition to be shot from a barrel, particularly training ammunition for mortars, which primer is armed shortly after firing.

It is an object of the present invention to avoid the abovenoted disadvantages of the prior art with respect to a projectile percussion primer employing a relatively movable firing pin and primencharged primer case, cap, or the like arranged axially one will automatically the other in a central recess or chamber in the projectile for engagement by the forces of inertia when the projectile strikes the target; the forwardmost of the primer element and firing pin element is fixedly secured with respect to the projectile while the rearwardmost one is axially displaceable with a spring interposed between the two. According to the present invention, the two elements are retained in their unarmed spaced position by means of a locking member that is displaceably mounted in a radial bore of the projectile opening into the chamber; the locking member being in turn held in its interposed position by means of a safety member being in turn held in its interposed position by means of a safety member that radially abuts the locking member on the outside until after firing and the projectile leaves the barrel, which corresponds to movement of the safety member axially from its blocking position.

According to a more specific aspect of the present invention, the locking member is constructed as a radially extending pin. Advantageously, a spring is employed to urge the pin away from its locking position so that after it is released it will automatically move from between the elements to allow the displaceable one of the elements, the firing pin or the primer, to move axially under the effect of its inertia upon striking the target.

With the locking member constructed as a pin, the front end wall of the cartridge case may be provided as the safety member, in accordance with the present invention. With such an arrangement, it is advantageous to provide a direct free fluid communication between the propellant charge pressure chamber and the outside of the locking member so that the propellant pressure, while the projectile is in the barrel, will tend to force the locking member into its locked position; thus, the propellant gases produced by the ignition of the propellant charge not only furnished the motor force for the projectile, but they also tend to hold the locking member in its blocking or locked position for a relatively long period of time. The period of time that locking is effective can simply be the time that it takes the projectile to leave the barrel of the firing device. However, such additional pneumatic blocking or holding of the locking member is of particular advantage with respect to projectiles that are not stabilized with respect to twist, because with such projectiles there is a relatively large amount of play between the barrel and the head of the projectile so that there is a danger that the locking member would move out of its blocked position prematurely once the projectile has been ejected from the cartridge case but while it is still within the barrel; thus, the pneumatic blocking described above would hold the locking member in its blocking position regardless of the amount of play once the projectile has left the cartridge case after firing.

Also, it is contemplated that the present invention may be used with a projectile that does not have a cartridge case, within the normal meaning of the term, but only has a bottom piece including the propellant charge; with such an arrangement, there is no front end of the cartridge case to serve as the safety member for holding the locking member. According to an embodiment of the present invention, a pin serves as the safety member and is axially displaceable in an axial blind bore rearwardly opening from the projectile body. Various specific constructions are contemplated. For example, the safety member may be held in its locking position by means of an intennediate or spacer disc provided immediately adjacent the bottom of the projectile, which disc retains the safety pin in its locked position by axial abutment until the projectile and disc exit from the barrel at which time the disc will become separated and fall away from the projectile due to drag and the like to release the safety pin for rearward movement and subsequent release of the locking member to am the projectile primer. Additionally, the safety pin may be held in its locking position against the bias of a spring so that rearward movement of the safety pin to arm the projectile is assured.

In order to assure that the projectile primer does not become armed at too great a distance or period of time from its barrel exit, it is proposed to provide the intermediate or spacer disc with a braking device, which will provide increased drag on the disc to assure its separation. The braking device is preferably constructed of two radially retractable and expandable blades spring urged into their expanded position where they provide a braking effect on the disc shortly after exit of the projectile from the barrel and accordingly a serial release of the safety pin, locking member and displaceable element.

BRIEF DESCRIPTION OF THE INVENTION Further objects, features and advantages of the present invention will become more clear from the following detailed description of the drawing, wherein:

FIG. 1 is a cross-sectional view taken through the axis of a projectile employing a locking pin and contained within a cartridge case;

FIG. 2 is a similar cross-sectional view showing a modification of the FIG. 1 device;

FIG. 3 is a partial cross-sectional view taken through the axis of another embodiment of the present invention employing a ball locking member;

FIGS. 3a and 3b show modifications of elements of the FIG. 3 device;

FIG. 4 is a cross-sectional view taken through the axis of a projectile and connected bottom piece according to a further embodiment of the present invention;

FIG. 5a is a cross-sectional view taken through the axis of the projectile at right angles to the view of FIG. 3; and

FIG. 5b is a cross-sectional view at right angles to the axis of the FIG. 5a device.

DETAILED DESCRIPTION OF THE INVENTION As shown in FIG. 1, the primer element, comprising a primer composition and primer case, is freely disposed in front of the projectile charge case 3 that encloses a smoke producing composition and within the axial bore or chamber 2 of the projectile 12. The percussion firing pin 6 is fixedly secured to the projectile 12 at the front end of the bore 2 so that its firing pin tip extends rearwardly toward the relatively movable primer element 1. A spacer compression spring 7 is provided between the front face of the bore 2 and the primer element 1.

A radial bore 8 or passageway is provided opening into the chamber 2 and slidably carries a locking pin or member 4 that is shown axially between the primer element and the firing pin element to prevent their relative displacement. The locking pin 4 is held in its illustrated locking position against the force of the ejection spring 8a by the overlapping front end of the cartridge case 5 that radially engages the head 4b of the locking pin 4; in the illustrated locking position, the shaft of the pin 4 extends into the chamber 2 to block forward movement of the primer element 1 toward the firing pin element 6 to thus assure safety of the projectile primer during transport.

The projectile is provided with a propellant charge 9 that when ignited produces propellant gases, which will rupture the case surrounding the charge 9 and pass through the radial outlet openings 10 into the propellant gas pressure chamber 11. With the buildup of pressure within the chamber 11 at the time of firing, the projectile will be forced forwardly out of the cartridge case 5 with the primer element being pressed rearwardly against the projectile charge within the casing 3 due to its inherent inertia caused by the acceleration of the projectile 12. Since the projectile l2 and the wall of the cartridge case 5 are not sealed off to be gastight with respect to the pressure chamber 11, the propellant gas pressure also becomes effective upon the head 4b of the locking pin 4 to press the locking pin 4 inwardly against the shoulder abutment 4a. With projectiles that are not stabilized with respect to twist, there is a relatively large amount of free play between the head of the projectile and the barrel so that the propellant gases may freely move between the projectile and the cartridge case or barrel wall to press the locking pin inwardly as described above to maintain the illustrated position of the locking pin 4 with respect to the projectile 12 throughout the entire extent of the firing device barrel, which barrel is not shown in the drawings. In this connection, the length of the retaining path, that is the path traveled by the projectile during which the locking pin is in its illustrated position, is depended upon the length of the barrel, on the one hand, and on the size and type of the propellant charge, on the other hand. In most cases, the length of this retaining path would correspond to the length of the firing barrel, thus ensuring the required barrel safety automatically. However, in cases where the retaining path would be shorter than the length of the barrel because of diminishing gas pressure or the absence of gas pressure for forcing the locking pin inwardly, the necessary barrel safety may be obtained in a simple manner merely by dimensioning the length of the locking pin 4 so that the pin 4 blocks the forward movement of the primer element 1 even when this pin 4 is pressed against the wall of the barrel under the effect of the ejection spring 8a. It is advantageous to construct the locking pin of a material substantially softer than the barrel wall to lessen the wear and tear on the barrel due to this sliding engagement.

After the projectile l2 exits from the barrel, the locking pin 4 is completely ejected from the radial bore 8 in all of the above cases by means of the compression spring 80, so that the primer body 1 is then free to move forwardly with respect to the firing pin element 6, that is, the projectile is armed. However, this ejection of the locking pin 4- takes a finite amount of time so that arming of the projectile will only be accomplished at a distance from the muzzle of the of the barrel correlated in part to the initial velocity imparted to the projectile, which produces a desired and sometimes required safety of the projectile primer immediately in front of the barrel. Since the primer element 1 is mechanically blocked throughout substantially the entire travel of the projectile through the barrel, the undesired and unintended ignition of the projectile primer is safely avoided while a small relatively weak spacer spring 7 may be employed for increasing the sensitivity of the projectile ignition at the target. Thus, it is seen that the heretofore conflicting requirements of safety during transport and within the barrel and sensitivity at the target may independently be satisfied. With such a weak construction of the spacer spring 7, the primer element 1 will strike the firing pin 6 within a relatively short time and distance after the projectile strikes the target. This means that the ignition of the projectiles primer will take place rapidly even when the projectile strikes soft ground so that the signaling charge contained within casing 3 will be released from the rear of the projectile advantageously while it is still above the ground so that it may be visible at great distances.

The device shown in FIG. 2 is identical with the device of FIG. 1, except for the differences to be described below. The projectile 12 has a smaller diameter to the rear of the locking pin 4 so that the space immediately radially outward of the locking pin 4 is in direct free communication with the pressure chamber 11 to the rear. Accordingly, the pressure of the gases produced by the propellant charge 9 may readily become effective upon the head 4b of the locking pin 4 more rapidly and more uniformly than in the FIG. 1 arrangement.

In the embodiment according to FIG. 3 of the present invention, the primer element 1 is provided with a primer charge and is fixedly mounted with respect to the projectile at the forward end of the chamber 2, and the firing pin element 6 is displaceably mounted in the rearward portion of the chamber 2 of the projectile. The projectile 12 is mounted within the cartridge case 5, which case carries the propellant percussion cap 14 in its bottom piece 13 and forwardly thereof the propellant charge 15. Between the bottom of the projectile l2 and the propellant charge 15, an intermediate or spacer disc 16 is provided in the bottom piece 13; an axially displaceable safety pin 18 is slidably mounted within the blind bore 17; the safety pin 18 rearwardly abuts against the spacer disc 16 and thus maintains the firing pin element 6 in its illustrated position by means of the interposed locking ball 19.

Upon firing, the projectile 12 with its primer element 1 and firing pin 6, and the spacer disc 16 are driven forwardly by the pressure of the propellant gases produced by the propellant charge 15; during this forward movement, the arrangement of the above-named elements is maintained as shown in FIG 3 until they leave the barrel of the firing device, not shown, that is, the safety pin 18 is retained in its blocking position by the disc 16 and accordingly the locking ball 19 and the firing pin 6 are likewise held in their locking position. Upon exit from the barrel, the gas pressure is suddenly decreased and the intennediate spacer disc 16 separates and falls away thus releasing the safety pin 18. The thus-released safety pin 18 subsequently lags behind and separates from the projectile 12, because of the relatively larger mass, and to thus clear the path for radial outward movement of the ball 19 in the radial bore 8 of the projectile. With radial outward movement of the ball 19, the firing pin 6 is also released so that it has complete freedom of axial movement for sliding forwardly in the chamber 2 by its won inertia upon the projectile l2 striking the target, which will ignite the charge of the primer element 1.

According to the modification of FIG. 3a, the safety pin 18 of FIG. 3 may be provided with a flangelike collar 18a at its rearward end. The bore 17 is enlarged twice towards its rear to provide room for the ejection spring 20 that will ensure ejection of the safety pin 18 after the disc has fallen away to further improve the reliability of arming.

The modification illustrated in FIG. 3b also improves the arming of the FIG. 3 device. The radial bore 8 is enlarged immediately radially outward of the locking ball 19 to prevent radial movement inwardly of the locking ball 19 in an undesired manner to its blocking position after the projectile has been armed.

The device of FIG. 4 is similar to that shown in FIG. 3 and corresponding parts have been provided with corresponding numerals so that their specific description will be dispensed with, except for the differences. In this embodiment, the bottom piece 13 and the projectile 12 are connected together by means of the intermediate or spacer disc 16; thus, a cartridge case with a tubular casing is not needed. The

' intermediate disc 16 has a rearward extension 21 provided with one interlocking annular collar 22 that establishes a relatively weak connection between the intermediate disc 16 and the bottom piece 13. Also, the intermediate disc is provided with a forward extension 23 having three annular collars 24 providing a relatively strong connection between the disc 16 and the projectile 12. In this embodiment, the safety pin 18 extends through a bore 25 provided in the disc 16 and aligned with the bore 17 so that the safety pin rearwardly abuts against the bottom piece 13. A cover plate 29, for example manufactured of a thermoplastic synthetic material, protects the percussion primer from outside influences.

After ignition of the propellant charge 15 by means of the propellant percussion cap 14, the annular bead 22 of the extension 21 is severed by the pressure of the propellant charge gases which develop; thus, the bottom piece 13 and the projectile 12 are separated from each other. Further, due to the pressure of the propellant gases, the projectile 12 together with the intermediate disc 16 is driven forwardly through the barrel (not shown) and the safety pin 18 is maintained in its locked position due to these pressure of the propellant gases. After exiting from the barrel, the intermediate disc 16 remains connected with the projectile and the safety pin 18 lags behind the projectile 13 due to its smaller mass so that it will rearwardly exit from the bore 25. Thereby, the locking ball 19 will be released to subsequently release the firing pin 6 to arm the projectile so that when the projectile 12 strikes the target, the primer element 1 may be ignited by the forward inertia movement of the firing pin 6.

In order to ensure a rapid and safe and controlled separation of the intermediate disc 16 from the projectile with the device of FIG. 3 after the projectile has left the barrel, the intermediate disc 16 is provided with a braking unit shown specifically in FIGS. 50 and 5b. This braking unit comprises two opposed pistons 27 that are respectively rigidly connected with vanes or wings 26, with a compression spring 28 being disposed between the pistons 27. After the projectile 12 and the intermediate disc 16 exit from the barrel, the braking wings 26 will be moved from their illustrated retracted position radially outward to project beyond the exterior of the disc 16 to provide a strong air resistant braking action which will produce a substantial force for separating the disc 16 from the projectile 12, due to the effect of the spring 28.

It is contemplated that all of the features shown in FIGS. 3, 3a and 3b may be combined in a single device. Also, the spring urging feature of FIG. 3a may be used in the device of FIG. 4. In all of the embodiments and modifications, either the firing pin or the primer element may be the forwardmost os the two with the rearwardmost one being axially displaceable.

Although the above embodiments and modifications have been shown as preferred illustrations, further modifications, variations and embodiments are contemplated within the spirit and scope of the present invention as defined by the following claims.

We claim:

1. A projectile including a cartridge case consisting at least of a bottom piece, said projectile having a forward end; a

substantially central axially extending chamber within said projectile; a firing pin element and a primer composition element axially spaced in aligned position within said chamber, the rearward one of said elements being mounted for axial displacement relative to said projectile forwardly in contact with the other of said elements, and the other of said elements being relatively fixedly mounted with respect to said projectile; said projectile; said projectile having a generally radially extending passage opening into said chamber; a locking member mounted for movement within said passage between a first position extending into said chamber immediately forward of said one of said elements and rearwardly spaced from the other of said elements to block movement of the one of said elements forwardly into engagement with the other of said elements and a second position generally radially spaced from said first position and said one of said elements to allow movement of said one of said elements forwardly into engagement with the other of said elements safety means normally radially engaging said locking member and holding it in its first position, and being mounted for movement with respect to said locking member to another position spaced from said locking member to allow movement of said locking member to its second position; said safety means being held in an unarmed position by a portion of the cartridge case for preventing actuation of said firing pin element prior to firing of the projectile.

2. The device of claim 1 wherein said cartridge case telescopically receives said projectile therein and has a forward tubular wall portion constituting at least in part said safety member.

3. The device of claim 1, wherein said locking member is a radially extending pin, and said cartridge case telescopically receives said projectile therein and has a forward tubular wall portion constituting at least in part said safety member.

4. The device of claim 1, wherein said locking member is a radially extending pin and said projectile includes an axially extending bore in communication with said generally radially extending passage and said safety member including a safety pin telescopically mounted for axial movement within said bore displaceable between said one position radially outside and in engagement with said locking pin in its first position and said another position axially spaced from said locking member; said axially extending bore being blind and opening rearwardly out of said projectile.

5. The device of claim 1, wherein said locking member is a radially extending pin and said projectile includes a spring normally biasing said locking member radially outward into its second position.

6. The device of claim 5, wherein said cartridge case telescopically receives said projectile therein and has a forward tubular wall portion constituting at least in part said safety member.

7. The device of claim 6, wherein at least one of said projectile and said cartridge case include propellant powder means for producing a propellant gas; said cartridge case and projectile forming therebetween a pressure chamber for receiving the propellant gases; said locking member having pressure surface means in direct free communication with said pressure chamber for producing a force in reaction to the propellant gases that biases said locking member into its first position.

8. The device of claim 1, wherein said locking member is a ball.

9. The device of claim 1, wherein said projectile includes an axially extending bore in communication with said generally radially extending passage and said safety member including a safety pin telescopically mounted for axial movement within said bore displaceable between said one position radially outside and in engagement with said locking pin in its first position and said another position axially spaced from said locking member; said axially extending bore being blind and opening rearwardly out of said projectile.

10. The device of claim 9, wherein said bottom piece has therein a propellant powder; said bottom piece abutting the rearward end of said safety pin in its said one position; means normally securing said body piece to said projectile and being rupturable upon firing of said propellant powder, including a spacer disc between said projectile and said bottom piece, said spacer disc having an axially extending bore aligned with said projectile axially extending bore receiving therein said safety pin; said spacer disc further having an extension provided with locking portions interengaging with said projectile and another extension having locking portions interengaging with said bottom piece.

11. The device of claim 9, including spring means biasing said safety pin rearwardly toward its said another position.

12. The device of claim 1 1, including a spacer disc abutting against the rear end of said projectile and constituting at least in part means for holding said safety pin in its said one position.

13. The device of claim 12, including air braking means automatically actuatable upon exit of said projectile from the firing barrel for providing said spacer disc with a substantial air friction separating force in the rearward direction relative to said projectile.

14. The device of claim 13, wherein said braking means includes at least two braking surfaces mounted in said disc for radial movement between a position retracted within said disc and a position extending radially outwardly from said disc beyond said projectile; and including spring means normally biasing said braking surfaces radially outwardly. 

1. A projectile including a cartridge case consisting at least of a bottom piece, said projectile having a forward end; a substantially central axially extending chamber within said projectile; a firing pin element and a primer composition element axially spaced in aligned position within said chamber, the rearward one of said elements being mounted for axial displacement relative to said projectile forwardly in contact with the other of said elements, and the other of said elements being relatively fixedly mounted with respect to said projectile; said projectile; said projectile having a generally radially extending passage opening into said chamber; a locking member mounted for movement within said passage between a first position extending into said chamber immediately forward of said one of said elements and rearwardly spaced from the other of said elements to block movement of the one of said elements forwardly into engagement with the other of said elements and a second position generally radially spaced from said first position and said one of said elements to allow movement of said one of said elements forwardly into engagement with the other of said elements safety means normally radially engaging said locking member and holding it in its first position, and being mounted for movement with respect to said locking member to another position spaced from said locking member to allow movement of said locking member to its secoNd position; said safety means being held in an unarmed position by a portion of the cartridge case for preventing actuation of said firing pin element prior to firing of the projectile.
 2. The device of claim 1 wherein said cartridge case telescopically receives said projectile therein and has a forward tubular wall portion constituting at least in part said safety member.
 3. The device of claim 1, wherein said locking member is a radially extending pin, and said cartridge case telescopically receives said projectile therein and has a forward tubular wall portion constituting at least in part said safety member.
 4. The device of claim 1, wherein said locking member is a radially extending pin and said projectile includes an axially extending bore in communication with said generally radially extending passage and said safety member including a safety pin telescopically mounted for axial movement within said bore displaceable between said one position radially outside and in engagement with said locking pin in its first position and said another position axially spaced from said locking member; said axially extending bore being blind and opening rearwardly out of said projectile.
 5. The device of claim 1, wherein said locking member is a radially extending pin and said projectile includes a spring normally biasing said locking member radially outward into its second position.
 6. The device of claim 5, wherein said cartridge case telescopically receives said projectile therein and has a forward tubular wall portion constituting at least in part said safety member.
 7. The device of claim 6, wherein at least one of said projectile and said cartridge case include propellant powder means for producing a propellant gas; said cartridge case and projectile forming therebetween a pressure chamber for receiving the propellant gases; said locking member having pressure surface means in direct free communication with said pressure chamber for producing a force in reaction to the propellant gases that biases said locking member into its first position.
 8. The device of claim 1, wherein said locking member is a ball.
 9. The device of claim 1, wherein said projectile includes an axially extending bore in communication with said generally radially extending passage and said safety member including a safety pin telescopically mounted for axial movement within said bore displaceable between said one position radially outside and in engagement with said locking pin in its first position and said another position axially spaced from said locking member; said axially extending bore being blind and opening rearwardly out of said projectile.
 10. The device of claim 9, wherein said bottom piece has therein a propellant powder; said bottom piece abutting the rearward end of said safety pin in its said one position; means normally securing said body piece to said projectile and being rupturable upon firing of said propellant powder, including a spacer disc between said projectile and said bottom piece, said spacer disc having an axially extending bore aligned with said projectile axially extending bore receiving therein said safety pin; said spacer disc further having an extension provided with locking portions interengaging with said projectile and another extension having locking portions interengaging with said bottom piece.
 11. The device of claim 9, including spring means biasing said safety pin rearwardly toward its said another position.
 12. The device of claim 11, including a spacer disc abutting against the rear end of said projectile and constituting at least in part means for holding said safety pin in its said one position.
 13. The device of claim 12, including air braking means automatically actuatable upon exit of said projectile from the firing barrel for providing said spacer disc with a substantial air friction separating force in the rearward direction relative to said projectile.
 14. The device of claim 13, wherein said braking means inCludes at least two braking surfaces mounted in said disc for radial movement between a position retracted within said disc and a position extending radially outwardly from said disc beyond said projectile; and including spring means normally biasing said braking surfaces radially outwardly. 